气候变化领域集成服务门户(CCPortal): Stable isotope characterisation of recent aragonite travertine deposits associated with the Fitero thermal waters (Spain)

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DOI	10.1007/s00531-020-01834-8
	Stable isotope characterisation of recent aragonite travertine deposits associated with the Fitero thermal waters (Spain)
	Blasco M.; Auqué L.F.; Gimeno M.J.; Asta M.P.; Mandado J.
发表日期	2020
ISSN	14373254
起始页码	877
结束页码	892
卷号	109 期号:3
英文摘要	The travertines of the Fitero thermal springs, with more than 98% of aragonite in most of the samples, are studied in this paper. The main objective is to improve the general understanding of aragonite precipitation, since the deposits of almost pure aragonite are very scarce. This study presents a complete mineralogical and isotopic characterisation, including the evaluation of the δ18O and δ13C fractionation during precipitation, as valuable information for paleoclimate and paleoenvironmental studies. Samples of a laminated travertine deposit constituted by almost pure aragonite were taken from a pipe discharging water at 40 °C. Waters suffered an important CO2 outgassing, as suggested by the geochemical calculations and the δ13C values of travertines and waters. This outgassing triggers the oversaturation and precipitation of carbonate phases. Temperature seems to be the main factor controlling the precipitation of aragonite or calcite, as checked by studying another travertine sample with higher calcite content. Various δ18O isotope fractionation equations for aragonite and calcite were used. The results indicate that precipitation took place close to equilibrium according to some of these equations. The fact that the equilibrium is maintained in a natural system with an important CO2 loss is surprising. However, it can be explained by an HCO3 −–water oxygen isotopic equilibrium and a direct transfer of the HCO3 − isotope signal to the carbonate without fractionation due to the fast CO2 loss and precipitation. Finally, considering other natural aragonite samples, a fractionation equation is defined for natural aragonite in the temperature range between 23 and 80 °C. © 2020, Geologische Vereinigung e.V. (GV).
英文关键词	Aragonite; Geothermal system; Isotope equilibrium; Stable isotope; Travertine
语种	英语
scopus关键词	aragonite; discharge; geochemistry; isotopic fractionation; mineralogy; precipitation (chemistry); stable isotope; thermal water; travertine; Spain
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147701
作者单位	Geochemical Modelling Group, Petrology and Geochemistry Area, Earth Sciences Department, University of Zaragoza, C/Pedro Cerbuna 12, Zaragoza, 50009, Spain; Institut Des Ciences de La Terre (ISTerre), Université Grenoble Alpes, CNRS, 1381 Rue de la Piscine, Gières, 38610, France
推荐引用方式 GB/T 7714	Blasco M.,Auqué L.F.,Gimeno M.J.,et al. Stable isotope characterisation of recent aragonite travertine deposits associated with the Fitero thermal waters (Spain)[J],2020,109(3).
APA	Blasco M.,Auqué L.F.,Gimeno M.J.,Asta M.P.,&Mandado J..(2020).Stable isotope characterisation of recent aragonite travertine deposits associated with the Fitero thermal waters (Spain).International Journal of Earth Sciences,109(3).
MLA	Blasco M.,et al."Stable isotope characterisation of recent aragonite travertine deposits associated with the Fitero thermal waters (Spain)".International Journal of Earth Sciences 109.3(2020).